This is a discussion on TPMS and turn indicators/blinkers within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; I mentioned this in my build thread, but in the interest of having this more easily found should anyone have ...

TPMS and turn indicators/blinkers

I mentioned this in my build thread, but in the interest of having this more easily found should anyone have the same issue I'm posting a thread here.

So, a couple weeks ago my TPMS light was flashing at me while I was stopped at a red light. It flashed for about 30 seconds or so and then disappeared. The odd thing was that I noticed my blinker indicator light on the dash was not blinking. I did not have a car in front of me or anything along those lines to see a reflection and determine if the actual blinkers were not blinking as well.

Then this past saturday when I was driving home from work, the TPMS light was going bananas on me. Blinking, staying on, turning off, etc. According to the manual the TPMS light should work in one of two ways. Either it comes on and stays on, indicating a tire out of range, or it blinks for a minute then stays on, indicating a problem with the system itself. The light was not behaving in either of these ways, but more concerning was that again my turn signals were not working whenever the TPMS light was either blinking or on. This time I was able to see reflections of my car and confirmed that the actual lights were not blinking.

I got home and checked tire pressures, and they were high probably due to the warm weather that day. I let a few psi out of all the tires and haven't had the TPMS light reappear since.

I called my local dealership and they say they have never heard of this happening, but that it is not normal operation. I will have to get this fixed as I have a set of winter wheels/tires and was planning on ignoring the TPMS light rather than pay to reset the system twice a year. Obviously if I can't use my turn signals when that light is on, though, that creates a problem.

So where we stand now is that I am going to put on one of the winter wheels after work to see if that replicates the problem (TPMS light on and blinkers not functioning). If so, I'll set up an appointment with the dealership so they can look at the car with the problem successfully replicated.

Ok, so I've been staying late at work often (upcoming audit) and with the girl having started school/still working her second job, I've always had too much to do upon getting home. Lame excuse out of the way, I haven't thrown a winter wheel on yet to try and replicate the issue. I did, however, have a new wrinkle crop up last night (the problem had not reoccurred all week until then). I'll let the video speak for itself:

Today I'm actually not working, so I will also be swapping a wheel to attempt to make the problem occur, and will post up the results of that endeavor.

Well, I threw one of my winter wheels on to try and trigger the TPMS light and...nothing. Full disclosure, I never actually jacked it down and drove on it. Although they are close to an exact fit for diameter, I didn't feel comfortable driving with one oddball wheel. I have no idea if I need to drive for a bit in order for the TPMS light to come on, so that is a variable in my test that I failed to control.

I'm just going to take it to the dealer with my video and see what they want to do for me.

So I confess, the problem was very sporadic for a long time and I did not take the car in. It would happen once a week or so with no clear precursor, so a combination of not wanting to deal with "no car" arrangements plus the highly probable likelihood that the dealership would be unable to replicate the issue kept the car out of the shop.

Then at the end of last week, it started happening every time I drove the car, after about 20-30 minutes of driving. It would start blinking, then go steady, then I would hear assorted noises behind the dash, then it would go off. Rinse and repeat. All the while the turn signal issue was present.

So I made an appointment and the car went in on Tuesday. They were able to "get the car to act up," and I was told that when they simply attempted a reset of the system, the control unit was unresponsive. So they ordered a new control unit, which was installed yesterday.

It seemed logical. They told me that during a routine reset of the system, at certain points the turn signals flash (indicating that the TPMS control unit is linked with the blinkers in some capacity) and even more interesting, the tech said that they also hear the same noises in the dash I was experiencing during the procedure. So, a crazy control unit could be responsible for my symptoms.

Well, I got the car back yesterday after work, and drove in today relishing my sense of safety due to functioning turn signals that weren't going to cut out on me at any given moment. Until I was parking outside my office. I was butchering a parallel parking job (I blame the fact that, of course, I can't locate my old driving position since the techs moved the seat) and the light starts blinking. I hit the turn signal and sure enough, nothing.

I called the dealership immediately and once the guy recognized who I was and I told him that the issue was back, there was a clear change in the tone of his voice haha. Recognition of a possible long haul, I think. He asked me to bring it in asap, and said "you'll need a car." I assume that means that they're going to have her for a while and I'll be getting a loaner.

As it was getting colder recently I've had the TPMS go on a number of times, then accordingly adjusted pressures. Never had ANY indication of a connection between turnn signals and TPMS... (3rd Gen, MY09)
And yes, the car has to drive to activate the TPMS, somehting of at least 20MpH for several minutes.

Ok, so the dealership had the car since Friday afternoon (it is now Wednesday). I got a call earlier today that they had ordered and received the Body Integrated Unit, and could I just get myself over there before 5 today with the extra key so they can reprogram the alarm and such after replacing it. Sweet! For those who don't know (I know I didn't), the BIU is essentially the ECU for everything that is not the drivetrain.

Well, just got another call a few minutes ago, they road tested it after replacing the BIU and the TPMS light came back on. No further info, just that they are on the line with Subaru's tech line again. I imagine some engineers either at SOA or in Japan are all

Alright, picked the car up this morning! They said they tracked it down to a bad relay. I'll just say two things:
1. The more electronic junk they put into cars, the more possible failure points.
2. My eyes are probably still going to be glancing down at the dash for a while after all this.

Other thoughts:

Rather than buying modifications, there should be a program for us where we can trade our car for base imprezas for a week. After driving that thing for 10 days, getting in my car is like getting in a whole new ride. Obviously the wrx has a lot more power than the impreza, but to be honest, that's not what I noticed the most getting back into it. The impreza's cvt did an admirable job delivering torque off the line, so for my commute (which is all city) it was perfectly fine. No, I'm noticing steering/turn-in and the brakes the most. Turning the impreza felt like if you tried walking with a dumbbell held straight out in front of you. I really felt the weight in the front of the car. Given that the basic platform is the same, engine is in the same place, etc, I'm impressed with how much more neutral the WRX feels compared to the car it is based on.

Yep. Had a couple days problem free. Then today I got in the car to drive to one of the other programs, and almost immediately the tpms light starts flashing and the turn signals no worky. The light came on steady, and unlike before, didn't cycle. It just stayed on. When I was close to getting back to my program, the hill assist light came on too.

On the way home, they both stayed on, and after about 45 minutes of driving the cruise control light started flashing at me as well. 2 minutes from home the tpms and hill assist lights went off, turn signal function returned, but the cruise control light continued to flash.

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